Support desktop notifications on Android

* doc/emacs/android.texi (Android Environment): Correct list of
permissions granted by default.

* doc/lispref/os.texi (Desktop Notifications): Document the new
function `android-notifications-notify' and its limitations.

* java/AndroidManifest.xml.in: Request notification permissions.

* java/org/gnu/emacs/EmacsDesktopNotification.java: New file.

* java/res/layout/sdk8_notifications_view.xml: New file holding
substitute notification widget definitions for Android versions
prior to 3.0.

* java/res/values/strings.xml: Remove inadvertently introduced
tag attribute.

* lisp/org/org-clock.el (haiku-notifications-notify): Correct
file name in function declaration.
(android-notifications-notify): New declaration.
(org-show-notification): Use `android-notifications-notify'.

* src/androidselect.c (android_init_emacs_desktop_notification)
(android_notifications_notify_1, Fandroid_notifications_notify):
New functions.
(init_androidselect, syms_of_androidselect): Initialize new
class and define new subr.

1 files changed, 31 insertions, 0 deletions

diff --git a/java/res/layout/sdk8_notifications_view.xml b/java/res/layout/sdk8_notifications_view.xml
new file mode 100644
index 00000000000..2daa5beea86
--- /dev/null
+++ b/java/res/layout/sdk8_notifications_view.xml
@@ -0,0 +1,31 @@
+<!-- Notification content widget tree for GNU Emacs on Android 2.3.
+
+Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>. -->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="vertical"
+              android:layout_width="match_parent"
+              android:layout_height="wrap_content"
+              android:padding="8dp">
+  <TextView android:id="@+id/sdk8_notifications_title"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"/>
+  <TextView android:id="@+id/sdk8_notifications_content"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"/>
+</LinearLayout>